"""Sidecar V2 — FastAPI server with multi-pool routing, admin API, dashboard SSE."""

import asyncio
import json
import os
import sys
import time
from collections.abc import AsyncGenerator
from contextlib import asynccontextmanager
from typing import Any, Optional

import logging
import structlog
from fastapi import Depends, FastAPI, HTTPException, Request, Response
from fastapi.responses import FileResponse, HTMLResponse, JSONResponse, StreamingResponse
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials

from config import config as app_config
from crypto import init_crypto, is_initialized
from pool_manager import PoolManager
from rate_limiter import PerBackendRateLimiter
from router import Router
from proxy import (
    handle_proxy_request,
    get_emergency_count,
    get_primary_wait_enter_count,
    get_primary_wait_recovery_count,
    get_primary_wait_exhausted_count,
)

from storage.db import init_db, create_tables, run_integrity_check, get_connection, _DB_PATH
from storage.backend_store import (
    create_backend, get_backend, list_backends, update_backend,
    delete_backend, get_pool_stats,
)
from storage.usage_store import get_total_stats, get_hourly_usage, get_daily_stats, aggregate_daily_stats
from storage.cooldown_store import get_cooldown_history
from storage.config_store import get_config, set_config, list_configs, delete_config
from storage.models import Backend, ModelMapping


# ──────────────────────────────────────────────────────────
# Logging
# ──────────────────────────────────────────────────────────
_LOG_FORMAT = os.getenv("LOG_FORMAT", "console").lower()
logging.basicConfig(level=logging.INFO)

structlog.configure(
    processors=[
        structlog.stdlib.filter_by_level,
        structlog.stdlib.add_logger_name,
        structlog.stdlib.add_log_level,
        structlog.stdlib.PositionalArgumentsFormatter(),
        structlog.processors.TimeStamper(fmt="iso"),
        structlog.processors.StackInfoRenderer(),
        structlog.processors.format_exc_info,
        structlog.processors.UnicodeDecoder(),
        (
            structlog.processors.JSONRenderer()
            if _LOG_FORMAT == "json"
            else structlog.dev.ConsoleRenderer()
        ),
    ],
    context_class=dict,
    logger_factory=structlog.stdlib.LoggerFactory(),
    wrapper_class=structlog.stdlib.BoundLogger,
    cache_logger_on_first_use=True,
)
logger: structlog.stdlib.BoundLogger = structlog.get_logger("sidecar_v2.server")


# ──────────────────────────────────────────────────────────
# Admin Auth middleware
# ──────────────────────────────────────────────────────────
_security = HTTPBearer(auto_error=False)


def verify_admin_token(
    credentials: Optional[HTTPAuthorizationCredentials] = Depends(_security),
) -> bool:
    """Verify Bearer Token against config.admin_token.

    If admin_token is empty, write operations are rejected.
    READ operations are allowed without auth for dashboard use.
    """
    if not app_config.admin_token:
        # No token configured — allow read, reject write (checked per-endpoint)
        if credentials is None:
            return False
        return False

    if credentials is None:
        return False

    return credentials.credentials == app_config.admin_token


def require_admin(credentials: Optional[HTTPAuthorizationCredentials] = Depends(_security)):
    """Require admin auth — raise 401 if not authorized."""
    if not app_config.admin_token:
        raise HTTPException(
            status_code=401,
            detail="Admin API not configured: set SIDECAR_ADMIN_TOKEN",
        )
    if credentials is None:
        raise HTTPException(
            status_code=401,
            detail="Missing Authorization header",
            headers={"WWW-Authenticate": "Bearer"},
        )
    if credentials.credentials != app_config.admin_token:
        raise HTTPException(
            status_code=401,
            detail="Invalid admin token",
        )


# ──────────────────────────────────────────────────────────
# Global runtime state
# ──────────────────────────────────────────────────────────
pool_manager: Optional[PoolManager] = None
rate_limiter: Optional[PerBackendRateLimiter] = None
router: Optional[Router] = None
start_time: float = 0.0

# In-memory metrics counters
_metrics_counters: dict[str, int] = {}
_metrics_lock = asyncio.Lock()


def _inc_metric(key: str, delta: int = 1) -> None:
    """Thread-safe counter increment (deferred via asyncio)."""
    _metrics_counters[key] = _metrics_counters.get(key, 0) + delta


def get_pm() -> PoolManager:
    assert pool_manager is not None
    return pool_manager


def get_rl() -> PerBackendRateLimiter:
    assert rate_limiter is not None
    return rate_limiter


def get_router() -> Router:
    assert router is not None
    return router


# ──────────────────────────────────────────────────────────
# Lifespan
# ──────────────────────────────────────────────────────────
@asynccontextmanager
async def lifespan(app: FastAPI) -> AsyncGenerator[None, Any]:
    global pool_manager, rate_limiter, router, start_time

    # P0: Encryption key is mandatory — refuse to start without it
    if not app_config.encryption_key:
        logger.critical(
            "missing_encryption_key",
            hint="Set SIDECAR_ENCRYPTION_KEY (64 hex chars). Refusing to start."
        )
        sys.exit(1)

    init_crypto(app_config.encryption_key)
    logger.info("crypto_initialized")

    # P0: Warn if admin_token not set
    if not app_config.admin_token:
        logger.warning(
            "admin_token_not_set",
            hint="Admin write endpoints disabled until SIDECAR_ADMIN_TOKEN is configured."
        )

    # Init DB
    init_db()
    create_tables()
    ok = run_integrity_check()
    if not ok:
        logger.error("db_integrity_check_failed")

    # Init runtime components
    pool_manager = PoolManager()
    rate_limiter = PerBackendRateLimiter(
        refill_interval_ms=app_config.rate_limiter_refill_interval_ms,
    )
    router = Router(pool_manager, rate_limiter)
    start_time = time.time()

    # Start background tasks
    health_task = asyncio.create_task(_health_check_loop())
    stats_task = asyncio.create_task(_stats_aggregation_loop())
    backup_task = asyncio.create_task(_backup_loop())

    logger.info(
        "sidecar_v2_started",
        host=app_config.host,
        port=app_config.port,
        metrics_port=app_config.metrics_port,
    )

    try:
        yield
    finally:
        for task in [health_task, stats_task, backup_task]:
            task.cancel()
            try:
                await task
            except asyncio.CancelledError:
                pass
        logger.info("sidecar_v2_stopped")


app = FastAPI(
    title="Sidecar V2 — Multi-Pool Provider Proxy",
    version="2.0.0",
    lifespan=lifespan,
)


# ──────────────────────────────────────────────────────────
# Background tasks
# ──────────────────────────────────────────────────────────

async def _health_check_loop() -> None:
    """Periodic health checks: clear expired cooldowns + active probing of backends."""
    from cooldown_manager import check_and_clear_cooldown
    import httpx

    while True:
        try:
            backends = list_backends(decrypt_key=True)
            for b in backends:
                # 1. Clear expired cooldowns
                if b.status == "cooling":
                    check_and_clear_cooldown(b.id)

                # 2. Active health probing for healthy/enabled backends
                if b.status == "healthy" and b.enabled:
                    try:
                        async with httpx.AsyncClient(timeout=httpx.Timeout(
                            app_config.health_check_timeout_seconds
                        )) as client:
                            probe_url = b.api_base_url.rstrip("/") + app_config.health_probe_endpoint
                            headers = {}
                            if b.api_key_plain:
                                headers["Authorization"] = f"Bearer {b.api_key_plain}"

                            start = time.monotonic()
                            resp = await client.get(probe_url, headers=headers)
                            elapsed_ms = int((time.monotonic() - start) * 1000)

                            # Update health state in DB
                            from storage.db import get_connection as _gc
                            with _gc() as conn:
                                conn.execute(
                                    """INSERT INTO backend_health
                                       (backend_id, state, last_latency_ms, last_status_code,
                                        last_check_at)
                                       VALUES (?, 'healthy', ?, ?, datetime('now'))
                                       ON CONFLICT(backend_id) DO UPDATE SET
                                       state = excluded.state,
                                       last_latency_ms = excluded.last_latency_ms,
                                       last_status_code = excluded.last_status_code,
                                       last_check_at = excluded.last_check_at""",
                                    (b.id, elapsed_ms, resp.status_code),
                                )
                                conn.commit()

                            logger.debug(
                                "health_probe_ok",
                                backend_id=b.id,
                                status=resp.status_code,
                                latency_ms=elapsed_ms,
                            )
                    except Exception as probe_err:
                        logger.warning(
                            "health_probe_failed",
                            backend_id=b.id,
                            error=str(probe_err),
                        )
                        # Mark as degraded
                        from storage.db import get_connection as _gc
                        with _gc() as conn:
                            conn.execute(
                                """INSERT INTO backend_health
                                   (backend_id, state, last_check_at)
                                   VALUES (?, 'degraded', datetime('now'))
                                   ON CONFLICT(backend_id) DO UPDATE SET
                                   state = 'degraded',
                                   last_check_at = excluded.last_check_at""",
                                (b.id,),
                            )
                            conn.execute(
                                """UPDATE backend_health SET
                                   consecutive_failures = consecutive_failures + 1
                                   WHERE backend_id = ?""",
                                (b.id,),
                            )
                            conn.commit()
        except Exception:
            logger.exception("health_check_error")
        await asyncio.sleep(app_config.health_check_interval_seconds)


async def _stats_aggregation_loop() -> None:
    """Periodically aggregate daily stats."""
    while True:
        try:
            today = time.strftime("%Y-%m-%d", time.gmtime())
            aggregate_daily_stats(today)
        except Exception:
            logger.exception("stats_aggregation_error")
        await asyncio.sleep(app_config.stats_refresh_interval_seconds)


async def _backup_loop() -> None:
    """Daily SQLite backup with retention."""
    import shutil

    while True:
        try:
            await asyncio.sleep(86400)  # 24 hours
            backup_dir = app_config.backup_dir
            if not backup_dir:
                continue

            os.makedirs(backup_dir, exist_ok=True)

            backup_name = f"sidecar_v2_{time.strftime('%Y%m%d_%H%M%S', time.gmtime())}.db"
            backup_path = os.path.join(backup_dir, backup_name)

            from storage.db import _DB_PATH as db_path
            import sqlite3

            source = sqlite3.connect(db_path)
            dest = sqlite3.connect(backup_path)
            source.backup(dest)
            dest.close()
            source.close()

            logger.info("db_backup_created", path=backup_path)

            # Retention: remove old backups
            retention_days = app_config.backup_retention_days
            cutoff = time.time() - retention_days * 86400
            for fname in os.listdir(backup_dir):
                if fname.startswith("sidecar_v2_") and fname.endswith(".db"):
                    fpath = os.path.join(backup_dir, fname)
                    if os.path.getmtime(fpath) < cutoff:
                        os.remove(fpath)
                        logger.info("db_backup_retired", path=fpath)

        except Exception:
            logger.exception("backup_error")


# ──────────────────────────────────────────────────────────
# Health / Metrics
# ──────────────────────────────────────────────────────────
@app.get("/health")
async def health() -> dict[str, Any]:
    return {
        "status": "ok",
        "version": "2.0.0",
        "uptime_seconds": int(time.time() - start_time),
    }


@app.get("/metrics")
async def metrics() -> Response:
    """Prometheus-compatible metrics endpoint."""
    lines = []

    # Pool provider counts
    pool_status = pool_manager.get_pool_status()
    for pool_name, stats in pool_status.items():
        for key, val in stats.items():
            lines.append(
                f"sidecar_pool_providers{{pool=\"{pool_name}\",type=\"{key}\"}} {val}"
            )

    # Cooldown status
    all_backends = list_backends(decrypt_key=False)
    cooling_count = sum(1 for b in all_backends if b.status == "cooling")
    lines.append(f"sidecar_cooldown_active {cooling_count}")

    # Emergency count (from proxy module)
    lines.append(f"sidecar_emergency_count {get_emergency_count()}")

    # Primary-Wait metrics
    lines.append(f"sidecar_primary_wait_enter_total {get_primary_wait_enter_count()}")
    lines.append(f"sidecar_primary_wait_recovery_total {get_primary_wait_recovery_count()}")
    lines.append(f"sidecar_primary_wait_exhausted_total {get_primary_wait_exhausted_count()}")

    # DB sizes
    from storage.db import get_db_sizes
    sizes = get_db_sizes()
    lines.append(f"sidecar_db_size_bytes {sizes.get('db_bytes', 0)}")
    lines.append(f"sidecar_wal_size_bytes {sizes.get('wal_bytes', 0)}")

    # Total stats
    total = get_total_stats()
    lines.append(f"sidecar_requests_total {total.get('total_requests', 0) or 0}")
    lines.append(f"sidecar_errors_total {total.get('total_errors', 0) or 0}")
    lines.append(f"sidecar_tokens_total {total.get('total_tokens', 0) or 0}")
    cost = total.get('total_cost', 0) or 0.0
    lines.append(f"sidecar_cost_total {cost}")

    # Uptime
    lines.append(f"sidecar_uptime_seconds {int(time.time() - start_time)}")

    return Response(
        content="\n".join(lines) + "\n",
        media_type="text/plain; charset=utf-8",
    )


# ──────────────────────────────────────────────────────────
# Dashboard SSE
# ──────────────────────────────────────────────────────────
@app.get("/dashboard/sse")
async def dashboard_sse() -> StreamingResponse:
    """SSE endpoint for real-time dashboard data."""

    async def event_generator():
        while True:
            try:
                pool_status = pool_manager.get_pool_status()
                total_stats = get_total_stats()
                all_backends = list_backends(decrypt_key=False)

                backends_list = []
                for b in all_backends:
                    rl_status = rate_limiter.get_status(b.id)
                    backends_list.append({
                        "id": b.id,
                        "name": b.name,
                        "label": b.label,
                        "pool": b.pool,
                        "enabled": b.enabled,
                        "status": b.status,
                        "rpm_limit": b.rpm_limit,
                        "cooldown_until": b.cooldown_until,
                        "consecutive_429_count": b.consecutive_429_count,
                        "model_count": len(b.model_mappings),
                        "rate_limiter": rl_status,
                    })

                snapshot = {
                    "type": "snapshot",
                    "pool": pool_status,
                    "total": total_stats,
                    "backends": backends_list,
                    "uptime_seconds": int(time.time() - start_time),
                    "timestamp": time.time(),
                }
                yield f"data: {json.dumps(snapshot)}\n\n"
            except Exception:
                logger.exception("sse_error")

            await asyncio.sleep(app_config.dashboard_sse_interval_seconds)

    return StreamingResponse(
        event_generator(),
        media_type="text/event-stream",
        headers={
            "Cache-Control": "no-cache",
            "Connection": "keep-alive",
            "X-Accel-Buffering": "no",
        },
    )


# ──────────────────────────────────────────────────────────
# Admin: Backend CRUD  (READ: public, WRITE: auth required)
# ──────────────────────────────────────────────────────────

@app.get("/api/admin/backends")
async def admin_list_backends(pool: Optional[str] = None) -> list[dict]:
    """List all backends with masked keys (public read)."""
    backends = list_backends(pool=pool, decrypt_key=True)
    return [b.to_dict(mask_key=True) for b in backends]


@app.get("/api/admin/backends/{backend_id}")
async def admin_get_backend(backend_id: str) -> dict:
    """Get a single backend (public read, key masked)."""
    b = get_backend(backend_id, decrypt_key=True)
    if b is None:
        raise HTTPException(404, "Backend not found")
    return b.to_dict(mask_key=True)


@app.post("/api/admin/backends")
async def admin_create_backend(
    body: dict[str, Any],
    _auth=Depends(require_admin),
) -> dict:
    """Create a new backend (auth required)."""
    required = ["name", "api_base_url", "api_key"]
    for field in required:
        if field not in body:
            raise HTTPException(400, f"Missing required field: {field}")

    model_mappings_raw = body.get("model_mappings", {})
    model_mappings = {}
    for canonical_name, mm in model_mappings_raw.items():
        model_mappings[canonical_name] = ModelMapping.from_dict(mm)

    backend = Backend(
        name=body["name"],
        label=body.get("label", ""),
        api_base_url=body["api_base_url"],
        api_key_plain=body["api_key"],
        api=body.get("api", "openai-completions"),
        timeout_seconds=body.get("timeout_seconds", 120),
        rpm_limit=body.get("rpm_limit", app_config.default_rpm_limit),
        pool=body.get("pool", "primary"),
        enabled=body.get("enabled", True),
        model_mappings=model_mappings,
        source=body.get("source", "webui"),
    )

    created = create_backend(backend)
    return created.to_dict(mask_key=True)


@app.put("/api/admin/backends/{backend_id}")
async def admin_update_backend(
    backend_id: str,
    body: dict[str, Any],
    _auth=Depends(require_admin),
) -> dict:
    """Update a backend (auth required)."""
    updates = dict(body)

    if "model_mappings" in updates:
        raw = updates["model_mappings"]
        updates["model_mappings"] = {
            k: ModelMapping.from_dict(v) for k, v in raw.items()
        }

    if "api_key" in updates:
        updates["api_key_plain"] = updates.pop("api_key")

    updated = update_backend(backend_id, updates)
    if updated is None:
        raise HTTPException(404, "Backend not found")
    return updated.to_dict(mask_key=True)


@app.delete("/api/admin/backends/{backend_id}")
async def admin_delete_backend(
    backend_id: str,
    _auth=Depends(require_admin),
) -> dict:
    """Delete a backend (auth required)."""
    ok = delete_backend(backend_id)
    if not ok:
        raise HTTPException(404, "Backend not found")
    return {"status": "deleted", "id": backend_id}


# ──────────────────────────────────────────────────────────
# Admin: Pool Status (public read)
# ──────────────────────────────────────────────────────────

@app.get("/api/admin/pools")
async def admin_pool_status() -> dict:
    return pool_manager.get_pool_status()


# ──────────────────────────────────────────────────────────
# Admin: Usage / Stats (public read)
# ──────────────────────────────────────────────────────────

@app.get("/api/admin/stats/total")
async def admin_total_stats() -> dict:
    return get_total_stats()


@app.get("/api/admin/stats/hourly")
async def admin_hourly_usage(
    backend_id: Optional[str] = None,
    hours: int = 168,
) -> list[dict]:
    since = None
    if hours > 0:
        since = time.strftime(
            "%Y-%m-%dT%H:%M:%SZ",
            time.gmtime(time.time() - hours * 3600),
        )
    return get_hourly_usage(backend_id=backend_id, since=since, limit=hours)


@app.get("/api/admin/stats/daily")
async def admin_daily_stats(days: int = 30) -> list[dict]:
    return get_daily_stats(days=days)


@app.get("/api/admin/stats/cooldown")
async def admin_cooldown_history(
    backend_id: Optional[str] = None,
    limit: int = 50,
) -> list[dict]:
    return get_cooldown_history(backend_id=backend_id, limit=limit)


# ──────────────────────────────────────────────────────────
# Admin: System Config (read public, write auth required)
# ──────────────────────────────────────────────────────────

@app.get("/api/admin/config")
async def admin_get_all_config() -> list[dict]:
    return list_configs()


@app.get("/api/admin/config/{key}")
async def admin_get_config(key: str) -> dict:
    value = get_config(key)
    if value is None:
        raise HTTPException(404, "Config not found")
    return {"key": key, "value": value}


@app.put("/api/admin/config/{key}")
async def admin_set_config(
    key: str,
    body: dict[str, Any],
    _auth=Depends(require_admin),
) -> dict:
    value = str(body.get("value", ""))
    description = str(body.get("description", ""))
    set_config(key, value, description)
    return {"key": key, "value": value}


@app.delete("/api/admin/config/{key}")
async def admin_delete_config(
    key: str,
    _auth=Depends(require_admin),
) -> dict:
    ok = delete_config(key)
    if not ok:
        raise HTTPException(404, "Config not found")
    return {"status": "deleted", "key": key}


# ──────────────────────────────────────────────────────────
# Dashboard HTML (public, but respects admin_token for writes in JS)
# ──────────────────────────────────────────────────────────

@app.get("/dashboard")
async def dashboard_html() -> HTMLResponse:
    dashboard_path = os.path.join(
        os.path.dirname(__file__), "dashboard.html"
    )
    if os.path.exists(dashboard_path):
        with open(dashboard_path, "r") as f:
            return HTMLResponse(f.read())
    return HTMLResponse("<h1>Dashboard not found</h1>", status_code=404)


# ──────────────────────────────────────────────────────────
# Proxy Endpoints
# ──────────────────────────────────────────────────────────

@app.post("/v1/chat/completions")
async def chat_completions(request: Request) -> Response:
    _inc_metric("proxy_requests_total")
    return await handle_proxy_request(
        pool_manager, rate_limiter, router, request, "/v1/chat/completions"
    )


@app.post("/v1/completions")
async def completions(request: Request) -> Response:
    return await handle_proxy_request(
        pool_manager, rate_limiter, router, request, "/v1/completions"
    )


@app.post("/v1/embeddings")
async def embeddings(request: Request) -> Response:
    return await handle_proxy_request(
        pool_manager, rate_limiter, router, request, "/v1/embeddings"
    )


@app.get("/v1/models")
@app.get("/v1/models/{model_id:path}")
async def list_models(request: Request, model_id: Optional[str] = None) -> Response:
    path = f"/v1/models/{model_id}" if model_id else "/v1/models"
    return await handle_proxy_request(
        pool_manager, rate_limiter, router, request, path
    )


@app.api_route("/{path:path}", methods=["GET", "POST", "PUT", "DELETE", "PATCH", "OPTIONS"])
async def catch_all(request: Request, path: str) -> Response:
    target_path = f"/{path}" if not path.startswith("/") else path
    return await handle_proxy_request(
        pool_manager, rate_limiter, router, request, target_path
    )


# ──────────────────────────────────────────────────────────
# Main
# ──────────────────────────────────────────────────────────

def main() -> None:
    import uvicorn

    uvicorn.run(
        "server:app",
        host=app_config.host,
        port=app_config.port,
        log_level=app_config.log_level.lower(),
    )


if __name__ == "__main__":
    main()